Save your skin as "
XRT_myskin1.jpg " ... for example. Car name, line, skin name, .jpg.
Make sure it is in LFS/data/skins folder. Also, you need to restart LFS for it to see new skins.
For other people to see it, you have to have S1 or S2, and upload the skin to
LFSWorld.net.
Also make sure it's 512x512 or 1024x1024 in resolution, and less than 400Kb in size ...
Oh, and when you are in the pits, create a new color, and choose your skin there.